It is known that carbon fiber reinforced plastics (CFRP) are alternately stacked as a fiber reinforced laminate to improve its strength. Such a fiber reinforced laminate is light in weight and high in rigidity, and is preferably used for shutter blades for a focal-plane shutter or the like which is used for a single lens reflex camera as an example of an optical apparatus and moves and stops for an extremely short time to cross the optical path.
Although a fiber reinforced laminate in which fibers are stacked, such as CFRP, has excellent characteristic, that is, is light in weight and high in strength, there occasionally occurs a “mesh opening” phenomenon that carbon fibers bend in the stage of stacking CFRP prepregs. Moreover, at the place of this mesh opening, light shielding ability can deteriorate.
Patent Literature 1 discloses a light shielding blade material for an optical apparatus in order to improve light shielding ability. It has a laminate structure having: a plastic film as a base material; light shielding coating films with light shielding ability which are formed on both surfaces; reinforcement members in which carbon fibers are made even as to their directions and which are stacked on the light shielding coating films; and lubricating black coating films which are formed on the reinforced members.
According to Patent Literature 1, by intervening the light shielding coating films between the carbon fiber reinforced plastic layers in the laminate constituting the blade material, light shielding ability needed as a shutter blade is obtained.